SMITH, T.L.; KARDONG, K.V.; BEVELANDER, G.S.; POVEL, G.D.E: Influence of prey odor concentration on the poststrike trailing behavior of the northern Pacific rattlesnake

Rattlesnakes strike and immediately release envenomated rodent prey and then begin a series of precise poststrike trailing behaviors, based primarily upon chemosensory cues, that allow the recovery of the prey. Following a strike, rattlesnakes can accurately discriminate between the trail of envenomated prey they struck from even a non-envenomated littermate suggesting that envenomation might help in resolving odor cues and enhance the perceptibility of the scent trail of the envenomated rodent. In previous studies, increased venom dose is correlated with increased interest by rattlesnakes suggesting further that concentration of produced poststrike odor is important. However during poststrike trailing, it is not clear whether rattlesnakes respond to any level above threshold equally or if they prefer trails with higher odor concentrations. Therefore the purpose of this study was to examine the effects, if any, of scent trail concentration upon poststrike behavior. To test this, we presented the snake with two paired prey odors in a Y-maze, one low concentration, one high concentration made with one or multiple passes, respectively, of the struck mouse. We found that concentration of the odor cue does influence the poststrike trailing of the snake. Rattlesnakes preferentially follow the “high” over “low” concentration poststrike odor trails. This suggests that poststrike trailing in rattlesnakes depend not upon a threshold level of prey odor but can detect actual differences in concentration of struck prey odor.